The present invention relates to a method for controlling a page printer such as a laser beam printer, and also to a controlling apparatus for a page printer.
Very recently, in the field of information processing apparatuses (referred to as an "IHS" hereinafter) such as a personal computer (referred to as a "PC" hereinafter) and a work station (referred to as a "WP" hereinafter), page printers are commonly used, which are typically referred as an optical printer, e.g., a laser beam printer (referred to as an "LBP" hereinafter), a light emitting diode printer (referred to as an "LEDP" hereinafter), and a liquid crystal shutter printer (referred to as an "LCSP" hereinafter). In general, a printer is designed to be connected via a printer control unit to a host computer such as PC and WC.
As described in, for instance, Japanese KOKAI (Disclosure) Patent Application No. 62-1735263, the conventional printer controlling apparatus is arranged as represented in FIG. 2. In this figure, a command series transmitted by a host computer (not shown) is drawn as a dot pattern into a first page region 231 within a page buffer 23 by way of a central processing apparatus (referred to as a "CPU" hereinafter). When the drawing of the character fonts, graphics, or image on the page buffer has been accomplished by means of 1-page command series, the data stored within the first page region are read by a printer adaptor 24, processed in a parallel-serial conversion, and thereafter output as a video signal to a printer engine unit 25. In the printer engine unit 25, the printing process is performed so as to print one page of a paper sheet.
In accordance with the above-described conventional printer controlling apparatus, a plurality of page regions 231, 232 and 233 are prepared for the page buffer 23. Also both drawing character fonts, graphics or images on the page buffer and printing operation are executed in a parallel mode by performing the data transfer (reading) from another page region to the printer engine 25 while drawing (writing) character fonts, graphics or images on one page region in order to increase the throughput.
However, in the prior art printer controlling apparatus, no care is taken to the controlling method for executing both the writing operation to the page buffer by way of drawing the character fonts, graphics, or images, and the reading operation from the page buffer by way of printing the data without any idle time. Even if the high-speed printer engine or page buffer constructed of a plurality of pages is employed, there is a problem that the printing operation is performed only at the lower speed than the engine speed since idle times are present in the various operating stages.